1) Field of the Invention
The present invention relates to an instrument for inserting an endoscope through the pharynx for the medical treatment.
2) Related Prior Art
An endoscope has been widely used to diagnose and treat tumors in the stomach, esophagus, etc. or lesions such as varices in the alimentary tract. However, the endoscope now in practical use has an outer diameter as large as about 10 mm, and thus operators' skill is required for the insertion of an endoscope with a large painful burden on the patients. Furthermore, the endoscope must be repeatedly inserted and withdrawn, depending on the required medical treatment, resulting in further increase in the burden on the patients.
On the other hand, a guide tube, as shown in FIG. 8A, is now commercially available to facilitate the insertion of an endoscope, thereby improving the operability and decreasing the burden on the patients. The guide tube comprises a tube body 21 of soft plastic resin and a mouthpiece 23 having a flange 24 at the rearward end.
The guide tube is used as follows:
At first, an endoscope is inserted through the throughhole of the guide tube and set thereto. Then, only the endoscope is moved forward through the throughhole of the guide tube and inserted from the oral cavity through the pharynx to make the forward end of the endoscope reach the esophagus. Then, the guide tube is slided down along the endoscope to insert the forward end of the guide tube into the pharynx region. Usually, the lumen of the pharynx region is bent and it is most difficult in the insertion of an endoscope to pass the endoscope through the pharynx region. By retaining the guide tube in the pharynx region, the successive insertion and withdrawing of the endoscope can be facilitated.
As materials for the tube body 21, mainly soft plastic resins such as polyvinyl chloride, etc. are used. The mouthpiece 23 serves to fix the guide tube by holding it between teeth of a patient after the guide tube has been inserted to the pharynx region. Thus, rigid or hard plastic resins are used as materials for the mouthpiece 23.
An example of practically using the guide tube for facilitated passage of an endoscope through the pharynx region is ligation of esophagal varices.
The ligation of esophagal varices is carried out as follows:
As shown in FIG. 8B, an endoscope 22 provided with a cylindrical device 26 at the forward end is inserted into the esophagus through the guide tube to make the device 26 reach a varix. The varix is sucked into the device 26, and then an elastic O ring expanded and mounted around the outer periphery of the inner tube of the device 26 is released from the forward end of the inner tube of the device 26 by pulling back a wire inserted through a forceps channel of the endoscope and fixed to the inner tube, thereby fixing the elastic O ring around the basis of the sucked polyp-like varix. That is, the varix is mechanically ligated by the contracting force of the elastic O ring to strangulate and slough off the ligated varix. The endoscope must be inserted and withdrawn for one ligation, and thus the guide tube is used for facilitating the repeated passage of the endoscope through the pharynx region (see U.S. Pat. No. 4,735,194 and a catalog of Stiegman-Golf Endoscopic Ligator, made by C. R. Bard, Inc, U.S.A. and distributed in Japan by K. K. Medicon, Japan).
However, the conventional guide tube, as shown in FIG. 8B has such a problem that, when the guide tube is bent, the tube body 21 is squashed at the bend 25 to narrow the throughhole, as shown in FIG. 8B, and thus when the guide tube is inserted to the pharynx region, the guide tube is bent in the pharynx region, deteriorating the smooth passage of an endoscope therethrough.
To solve the problem, the throughhole of the guide tube must be broadened. That is, the guide tube has a larger outer diameter than the necessary one, resulting in a further increase in the burden on the patients. Furthermore, in the case of bleeding from the esophagus, the blood is washed with water or physiological saline and discharged from the esophagus by aspiration. In the case of aspiration, there is such a problem that air leaks in through the guide tube, making the aspiration force insufficient, or when air is blown into the esophagus to broaden the endoscopic sight within the esophagus on the other hand, the blown air leaks out through the guide tube, resulting in a failure to sufficiently broaden the endoscopic sight.
In the case of inserting an endoscope into the pharynx region, patients often bite the endoscope due to patients' high tension, causing an endoscope trouble or disorder. To solve the problem, a patient is allowed to hold a mouthpiece 27 between teeth, as shown in FIG. 9A, and an endoscope 22 is inserted into the patient's pharynx region 20 through the throughhole of the mouthpiece 27. However, in the case of the mouthpiece of such a conventional type as shown in FIG. 9A, the endoscope is sometimes to be removed after one medical treatment, and the endoscope must be again inserted for a successive medical treatment through the mouthpiece, whereby the treating time is so prolonged as to give pains to the patient. Furthermore, it is quite difficult to insert a guide tube through the throughhole of the mouthpiece held between the teeth, and thus the mouthpiece of conventional type is not practically applicable to the guide tube.